1. Field of the Invention
The invention relates to surface particle monitoring systems and, more particularly, to a surface particle sampling head for such systems.
2. Description of the Background Art
Surface particle monitoring equipment is used in semiconductor processing equipment to capture and analyze contaminant particles within a reaction chamber and, in general, within any cleanroom environment. Such analysis is particularly important following wet cleaning of a reaction chamber. The monitoring equipment is used to ensure that the cleaning procedures are sufficient to eliminate residual particulate contaminants, to determine sources of contaminants and to determine which cleaning procedures produce optimal cleaning results.
One example of surface particle monitoring equipment is the QIII manufactured by Dryden Manufacturing of Fremont, Calif. QIII is a registered trademark of Dryden Manufacturing. This equipment is the subject matter of U.S. Pat. 5,253,538, issued Oct. 19, 1993, the disclosure of which is incorporated herein by reference. The surface particle monitoring equipment contains a particle detector and a sampling head. The sampling head is also known in the art as a scanner. In use, the sampling head is positioned against a surface, e.g., an inner wall of a reaction chamber of a semiconductor processing system, to capture particulate contaminants on the surface. The particles are typically removed from the surface by air flow, e.g., a 1 cfm flow rate, that fluidizes the particles. Two hoses, or conduits, connect the sampling head to the particle detector such that air flow from one hose passes over the surface and fluidizes the particles that lie on the surface beneath the sampling head. From the sampling head, the particles are carried by the second hose to the particle detector.
The particle detector analyzes the captured particles to generate a particle concentration per inch (or centimeter) squared. Such concentration values are very useful in characterizing the effectiveness of chamber cleaning procedures.
The sampling heads used in the prior art are fabricated in a variety of sizes and shapes. For example, the probe, the portion of the sampling head that contacts the surface to be sampled, is available in various diameters, e.g., two inch or three inch diameter models. However, the probes form an integral portion of the sampling head and are not removable. As such, multiple sampling heads must be purchased to facilitate the use of various sized probes.
An additional disadvantage of the prior art sampling heads is that the surface of the probe (the face plate) is planar to match the typical surface shape encountered in semiconductor processing systems. Such planar face plates of the present probes limit the use of the sampling heads to effectively analyzing flat surfaces.
Other alternatives to the prior art sampling head structure include a handle that is either straight, i.e., the handle portion is in-line with the probe, or ninety degrees, i.e., the handle portion is orthogonal to the probe. In the prior art, the relative positions of the handle and probe are always fixed. Having a fixed position for the probe, makes it impossible for the sampling head to be used in certain applications where the sampling head will not fit into a portion of the chamber.
Therefore, a need exists in the art for a sampling head that is rotatable to allow for flexible positioning of the probe relative to the handle and to permit self alignment of the probe with the surface to be sampled. Also, it would be advantageous to have a detachable face plate that allows various shaped face plates to be easily interchanged.